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Evidence-Based Practice

Developed to facilitate research for nursing students attending classes at Modesto Junior College

Primary vs. Secondary Sources

Primary sources in the field of medical and health sciences are typically journal articles detailing original research. Researchers design and implement a study, then publish the details of that study in a journal. These article usually include:

  • An in-depth description of experiments, including how they were designed, implemented, and summarizing the results 
  • References to other relevant experiments and research
  • Relevant source materials that  help reader understand the study

Primary sources tend to be very specific and can be difficult to read unless you are an expert in the subject area the research covers. They are written by experts, and their target audience is usually other experts within the same field. There is an assumption that readers of medical journals, for instance, have a grasp of core medical concepts and medical terminology.

Primary sources are important because they are often the original sources of new knowledge. An example of a primary sources is a quantitative or qualitative research study that describes an intervention and its outcome on a specific population.

Secondary sources are materials that provide interpretations, explanations, and descriptions of primary sources.  Common secondary sources are newspapers and magazines, and even review articles in journals. These articles usually include:

  • Summary of experiment/research
  • Context/perspective
  • Facts

This type of information is written in language that is more accessible to a broader audience--not just for experts and scholars. It lacks the detailed description of the experiments and research found in primary sources, and tends to simply summarize the results of the original research. 

Not All Evidence is Created Equal

Evidence comes in many forms and varies in quality. Within research, there is a recognized hierarchy of reliability which can be used as a guide when considering the effectiveness of evidence. This hierarchy is often communicated visually as a pyramid.

Evidence Hierarchy Pyramid

Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence based medicine: what it is and what it isn't. BMJ. 1996 Jan 13;312(7023):71-2